The controlled collection, processing, and distribution of clinical specimens from leukemia patients is critical to the accurate and efficient acquisition of genomic data required for this program project. A repository of standardized tumor gene expression data corresponding to these specimens will also aid in elucidating the genomic basis of AML. According, this Core has two Specific Aims: 1) We will collect, store, and process tissue specimens from all patients with a diagnosis of AML and MDS seen at this institution. We will include malignant cell populations from bone marrow aspirates and peripheral blood as well as skin biopsy and buccal lavage specimens representing non-malignant cell populations. We will collect specimens throughout each patient's disease course (initial presentation, remission, relapse) and, where appropriate, archival specimens from previous malignancies will be retrieved. We will process specimens to cellular RNA, genomic DNA, and cellular protein extracts as required for each study. Particular attention to specimen procurement (e.g. rapid processing of leukemia cells to preserve transcript profiles) and quality control will be practiced. 2) Using the Affymetrix GeneChip (R) platform, we will generate expression information on 39,000 gene transcripts from all AML specimens collected during this study. Along with clinical and laboratory data obtained by the Clinical Database Core, we will make this collective data repository available to the Biostatistics Core to test and validate hypotheses as the corresponding samples from the specimen repository are utilized for sequencing analysis in Project 1.